1. Field of the Invention
This invention relates to light sources in general and more particularly to a light source for a borescope/fiberscope visual system which is portable and specifically designed for safe use in hazardous locations.
2. Description of the Prior Art
Borescopes, fiberscopes and fiberoptic light guides connected to an electrical source are used to visually inspect the internal condition of a wide variety of objects where disassembly is costly, where disassembly is not possible and in medical applications. These instruments are in use today and are well known in the field.
The use of these instruments has been limited or prohibited, however, where there is a real risk of fire or explosion from the heat of the projection lamps, sparking or a failure of the electric circuit. Hazardous environments which provide a high risk of fire or explosion with the use of a light source may be found in nearly any industry. Some examples of such hazardous environments include those found on off shore oil rigs, on board ships, in the space program, in the munitions industry, during military and commercial aircraft maintenance, and in relation to electrical utility companies for industrial turbines, mines, food processing plants such as flour mills, plastics, oil refineries and the chemical industry. In addition, hazardous environments exist in health care facilities.
The need for a fiberoptic light source for use in hazardous conditions has been previously recognized in the field. Previous attempts, however, to provide a safe and effective light source for continuous use in hazardous locations have been unsuccessful.
For example, some prior art devices have attempted to avoid the use of an external electrical power source in order to ensure safety. These devices, however, have lacked sufficient power to provide adequate illumination.
Other prior art devices have provided cutoff switches that cause the device to stop operating when it becomes overheated. Such devices, however, fail to provide continuous illumination for an adequate period of time.
Certain prior art devices, such as the energizer disclosed in U.S. Pat. No. 3,681,592 do contain a number of safety features. These devices, however, do not provide all the available safety features necessary to ensure continuous, safe operation in a hazardous location.
Finally, to the degree these prior art devices may be considered safe for use in hazardous environments, none of these devices are both portable and able to provide continuous illumination.